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By Steven J. Page, John A. Organiscak

The amount of airborne respirable dust generated from break- age of different coals varies widely. This research was conducted to identify the facets of airborne respirable dust liberation from the coal product. Laboratory crushing experiments were conducted on a range of low to high volatile bituminous coals to investigate the various factors influencing airborne respirable dust generation. Bituminous coal samples from 8 mines (5 U.S. and 3 Polish) were uniformly prepared and processed through a double roll crusher located in a low air velocity wind tunnel. Experimental factors studied included inherent coal seam constituents, specific energy of crushing, product size characteristics, dust cloud electrostatic field, and specific quantity of airborne respirable dust generated. The results of this investigation build upon previously published results, which indicated that a combination of several factors are associated with the generation of airborne respirable dust. One factor involved is the effect of coal rank, described by the inherent moist fuel ratio, on the product size characteristics, defined by Schuhmann size function parameters. However, since coals of high moist fuel ratio (high rank) are generally more extensively cleated, it is suggested in the present work that the degree of cleating is directly responsible for the quantity of respirable-sized particles produced in the crushed product material for eastern U.S. coals. This is implied by the relationship of ash content and at least one mineral constituent (pyrite, determined from pyritic sulfur analysis) to the percentage of airborne respirable dust. To validate this hypothesis, a description is offered that is based on known coal petrography. Another key factor is the effect of air dry loss moisture in the coal seam on the breakage-induced electrostatic field of airborne dust. The air dry loss moisture factor appears to control the amount of airborne respirable dust that is liberated from the product. The resultant effect of these factors is that different percentages of coal particles smaller than 10 µm are dispersed as airborne respirable dust with a well-defined peak in the normalized airborne respirable dust for a narrow range of air dry loss moisture - ash ratios. A clear delineation of coals, based on well-known proximate analysis characteristics, that generate the most respirable dust appears to be possible. It was also shown that the dust-generating characteristics of coals could be reasonably described by both the moist fuel ratio

This Bureau of Mines report and its companion report (Information Circular 9142) have been prepared to assist in the preparation of prefeasibility type estimates for capital and operating costs of beneficiation of various types of mineral occurrences using current technology. The handbook provides a convenient costing procedure based on the summation of the costs for the unit processes required in any particular mining or mineral processing operation. The costing handbook consists of a series of costing sections, each corresponding to a specific mineral processing unit process. Contained within each section is the methodology to estimate either the capital or operating cost for that unit process. The unit process sections may be used to generate, in January 1984 dollars, costs through the use of either costing curves or formulae representing the prevailing technology. The mineral processing handbook includes individual cost estimation sections for unit operations associated with comminution, beneficiation, solid-liquid separation, hydrometallurgy, and special applications as well as infrastructure and plant general and administrative costs. When using this system for estimating cost data for a mineral processing facility or for checking or verifying processing costs from an existing facility, a minimum amount of background information is necessary.

Jan 1, 1987

By J. Bootle

Marrow vein deposits will continue to be an important source of valuable minerals. Productivity per manshift is not keeping pace with operating costs. Increased mechanization of stoping operations must be obtained to create greater productivity at a reduced cost per ton. This application of mechanization may be to either present methods or to newly developed concepts. The total mine unit operations will be effected by increased productivity. Two approaches to increasing the mechanization of narrow vein stoping were studied with the intention of increasing stope productivity and decreasing stoping costs. A method of bringing efficient rubber-tired equipment into narrow cut and fill stopes was designed. It proposes to provide stope access by way of a ramp constructed on the stope fill. Impact breaking equipment was studied and specific applications proposed.

Jan 1, 1977

By Carl N. Anderson

This paper, which is one of a group presented by the United States Bureau of Mines covering mining practice in different districts, deals in particular with the methods employed in mining the horizontal type of zinc-lead orebodies of the West Baxter area of the Tri-State zinc and lead district. These orebodies, locally termed "sheet-ground" bodies, with their relatively low working faces and low tenor of zinc and lead, require changes in the mining practice which is used in the balance of the district. In addition to the general mining methods, this paper also describes the system of hand sorting employed prior to the direct milling of the ore. The Hartley mine is situated mile west of Baxter Springs, Kans., as indicated in Figure 1. Its general outline and the location of the shafts with respect to the milling plant are shown in Figure 2.

Jan 1, 1932

By Melvin P. Silverman

The literature on methane-oxidizing bacteria is reviewed in regard to (1) the growth and isolation of cultures by special techniques; (2) the distribution of these organisms in nature and descriptions of individual species; (3) the physiology of methane-oxidizing bacteria as influenced by temperature, light, pH, aerobiosis versus anaerobiosis, and carbon and nitrogen sources; and (4) the biochemistry of methane oxidation revealed by studies with intact cells and subcellular systems. Present practical applications of methane-oxidizing bacteria are limited to prospecting for natural gas and petroleum deposits. Desirable areas for future research are discussed as well as some possible applications such as (1) the removal and/or early detection of methane gas in coal mines by intact cells or enzyme preparations; (2) the generation of electrical energy by microbial fuel cells using methane as fuel; (3) the growth of methane-oxidizing bacteria on methane for their food value; (4) the purification of hydrocarbon gas mixtures using methane-oxidizing or other alkane-oxidizing bacteria; and (5) the synthesis of methane from mixtures of H2 and CO or H2 and CO2 by me thane-forming bacteria.

Jan 1, 1964

By L. D. Tracy

"This paper represents work conducted by the Bureau of Mines in cooperation with the Illinois Geological Survey and the Engineering Experiment Station of the University of Illinois.IntroductionThe present report covers conditions and mining royalties in District VIII of the coal fields of Illinois, as designated by the Illinois Geological Survey. The various districts have been described in the reports on the Illinois coal-mining investigations, carried on cooperatively by the Illinois Geological Survey, the engineering experiment station of the University of Illinois, and the U. S. Bureau of Mines. This district includes Vermilion and Edgar Counties, but as the coal-mining operations in Edgar County amounted to only 827 tons in 1923, the data here given have been confined to Vermilion County.A similar report on District VI (Williamson and Franklin Counties) has been issued as Serial 2722 of the Bureau of Minos.A description of geological and mining conditions, and a discussion of market and transportation facilities, have been included because these have an important bearing on the royalties specified and the general conditions of the lease.Mining ConditionsDistrict VIII is better known as the Danville district and in 1923 produced 4,177,000 tons of coal, or approximately L per cent of the total output for the entire State for that year, which was 79,300,000 tons."

Apr 1, 1926

By W. M. Myers

[The principle of the application of electrolytes for deflocculation of fine materials in order that impurities may settle out, and the subsequent flocculation of the suspended particles by a different reagent, is well known and has been applied successfully to clays. Flocculation is also applied with success to ore slimes. Thus certain electrolytes, particularly alkalies added to a suspension of colloidal particles cause deflocculation so that, suspension may be-maintained indefinitely. The addition of bother electrolytes particularly acids, on the contrary produce's flocculation and the articles produce's are rapidly precipitated from suspension leaving a clear liquid above: the precipitated mass. Salts of trivalent elements such as aluminum act similarly. Due to its cheapness the double sulphate of aluminum and potassium, ordinary alum, has been used extensively for treating clays. These properties of electrolytes. and. their utilization in the commercial: preparation of clays have been described in publications of the Bureau of Mines.2]

Jan 1, 1927

By Wilton Johnson

Native asphalt was produced by three companies in two States, Texas and Utah. Bituminous limestone, used primarily as a paving material for street and road repair, was produced by one firm, R. L. White Co., Uvalde County, TX. Gilsonite, a solidified hydrocarbon found only in Colorado and Utah, was mined by two firms, American Gilsonite Co., a division of Chevron Resources Co. (a subsidiary of Standard Oil Co. of California), and Ziegler Chemical and Mineral Corp. Hydrocarbon Mining Co. (a subsidiary of Oberon Oil Inc., a Utah corporation) closed its mining operation during the year.

Jan 1, 1988

By Melvin P. Silverman

The literature on methane-oxidizing bacteria is reviewed in regard to (1) the growth and isolation of cultures by special techniques; (2) the distribution of these organisms in nature and descriptions of individual species; (3) the physiology of methane-oxidizing bacteria as influenced by temperature, light, pH, aerobiosis versus anaerobiosis, and carbon and nitrogen sources; and (4) the biochemistry of methane oxidation revealed by studies with intact cells and subcellular systems. Present practical applications of methane-oxidizing bacteria are limited to prospecting for natural gas and petroleum deposits. Desirable areas for future research are discussed as well as some possible applications such as (1) the removal and/or early detection of methane gas in coal mines by intact culls or enzyme preparations; (2) the generation of electrical energy by microbial fuel cells using methane as fuel; (3) the growth of methane-oxidizing bacteria on methane fur their food value; (4) the purification of hydrocarbon gas mixtures using methane-oxidizing or other alkane-oxidizing bacteria; and (5) the synthesis of methane from mixtures of H2 and CO or H2 and CO2 by methane-forming bacteria.

Jan 1, 1964

By James W. Ballard, H. H. Schrenk

"The X-ray method of quantitative determination is advantageous because it permits determination of compounds rather -than ions or elements; for example, the direct determination of quartz in silicates,4/,5/,6/ The method also takes into account the finest particles of a sample, which may be lost in wet chemical methods because of solubility or in petrographic methods because of limitation of the microscope. The sample is usually reduced to a powder and is easily prepared,7/ only a few milligrams of material being necessary. The sample and its chemical composition are not destroyed and may be used for further analysis by X-ray diffraction or by other methods.This paper presents in detail some of the more essential problems that arise in the application of X-ray diffraction to quantitative chemical analysis, Photometric measurements are discussed in connection with line intensities and the choice of X-ray film. The internal standard method, successfully used in spectrographic analysis, is applied.Copper K-alpha X-rays from a demountable research-type X-ray tube were used with a camera of 20 centimeters radius with a cast-lead-slit collimating system. A combination of a tilted wedge and a lead-slit collimating system permitted irradiation of a large amount of sample with X-rays. This tended to minimize errors due to possible inhonogeneity of the sample, to decrease the time of exposure, and to keep the lines on the X-ray film to a minimum width. There was sufficient dispersion of the lines for satisfactory analysis of most samples. Power was furnished the tube by a. source of constant high potential consisting of a synchronous motor generator furnishing 500-cycle power to a 100-kv. transformer, rectifying valves, and a condenser filter circuit. The X-ray tube was operated as a gas-type tube at 35 kv, and 20 ma,, the exposure times varying from 1 to 2 hours. The constant output of X-rays from the tube, indicated bar an exposure meter built for the purpose, was satisfactory.The recording microphotometer8/has been described. It was found preferable to a nonrecording instrument for measuring blackening of lines above a background on X-ray films. This background, which usually occurs, is sometimes complicated by numerous peaks from lines of complex diffraction patterns. is microphotometer record of the pattern, therefore, facilitates the location of the background 'and the measurement of the heights of the peaks and thus contributes to the accuracy of a determination."

Jun 1, 1946

From the time of its establishment in 1910, the Federal Bureau of Nines has studied the carbonization of coal, and a considerable part of this effort has been devoted to investigations in the so-called low-temperature carbonization range, 450° to 700° C., in which there is minimum decomposition of primary products and maximum yield of Liquids - a yield two to threefold the amount produced in high-temperature carbonization at 900° to 1,200° C, The solid residue, char, or coke, produced in low-temperature carbonization is 70 to 80 percent of the coal charged and may be used directly as a smokeless fuel or for blending with coals to produce metallurgical coke, Although some thought was given to the use of tar and to the illuminating value of gas derived from lm-temperature carbonization, the main emphasis in early work of the Bureau of Mines was on the preparation of smokeless fuel, especially for home use, For example, a carbonizer was designed and operated for making char and briquets from North Dakota lignite without recovery of by- products; however, the shortage of high-temperature coal-tar products in the United States during World War I had already indicated the potential usefulness of low-temperature tar.

Jan 1, 1959

By W. L. Dare

This publication is one of a series prepared by the Federal Bureau of Mines on methods and costs of producing uranium ore on the Colorado Plateau. The information it contains was gathered in 1955-58 and applies to eight small operations. (See fig. 1.) Mining costs have increased since the data were I collected, but the information should be helpful in estimating future costs I at similar deposits. The Bureau of Mines had early experience in the production of carnotite-type ores on the Colorado Plateau.3 4/ Under a cooperative agreement with the National Radium Institute in 1914-16, the Bureau mined and concentrated carnotite ore for recovery of radium, uranium, and vanadium. The ore was taken from claims in or near Long Park Montrose County, Colo., about 3 mi. south of La Salle Mining Co.'s La Salle mine, which is one of the mines described in this report. The Bureau leased the claims from Crucible Steel Mining & Milling Co., a subsidiary of Crucible Steel Co. of America, and from 1914 to 1916 produced 990 tons of high-grade ore, containing 2.6 pct. U308, and about 2,000 tons of mill-grade ore, containing 0.85 pct. U308. The high-grade ore was shipped directly to a radium-recovery plant built in Denver in 1914 under the cooperative agreement. There, commercial methods of extracting uranium, vanadium, and radium from carnotite ores were developed by Bureau personnel. The lower grade ore was concentrated at a small mill in Long Park before being shipped to Denver. The final recovery was 69,000 lb. of U308 and 8.8 g. of radium. The direct mining cost of producing the high-grade ore, including the labor to hand sort and sack it, was $35.96 per ton. Freighting the ore 58 miles to Placerville, Colo., the nearest rail point on the Rio Grande Southern Railway, cost $25.28 per ton, which included $4.55 per ton for ore bags and twine. Four-or six-horse teams pulled two wagons in tandem and made the

Jan 1, 1961

By M. M. Fine

Chalcocite flotation concentrates (26-34 percent Cu and 6-7 percent S) were roasted in air to determine sulfur elimination as a function of temperature, airflow rate, and residence time. Fluosolids roasting was evaluated batchwise and continuously in a 4-inch fluid-bed reactor. Kiln roasting tests were carried out in a 4-inch ID by 6-inch-long rotary drum. Pelletizing the very fine concentrates prior to roasting was essential to minimize dust losses and accretions. Concentrate pellets, sized minus 10 plus 20 mesh and bonded with 2 percent bentonite, were excellent feed for fluosol¬ids roasting and limited dust losses to 10 percent or less. One-fourth-inch pellets were best suited to kiln roasting. Both techniques were capable of producing copper calcines analyzing well under 1 percent residual sulfur when operated at 900° C with average retention times of 3 to 4 hours. Calcined pellets were strong, porous, and readily reducible.

Jan 1, 1970

By Harold J. Rose

The economic situation in Switzerland during recent years has resulted in theoretical studies , engineering development work , and many commercial installations of ingenious methods for using energy more efficiently . The purpose of the present investigation was to learn of recent Swiss developments for the more effective use of coal , which comprises 98.9 percent of the romaining known mineral - fuel reserves of the United States .

Jun 1, 1947

By D. L. Paulson

The Bureau of Mines is investigating pyrometallurgical and chemical methods for extracting copper from sulfide ores under conditions that provide for control of gaseous and solid emissions. Under this program, a new electrothermic reduction process was developed to produce blister copper after collecting essentially all of the sulfur by a single-unit operation. The process feasibility was indicated by a laboratory-scale investigation that demonstrated chalcopyrite concentrate can be roasted to less than 1 percent sulfur and that the resulting calcine can be reduced with carbon to blister copper by a cyclic process in a single arc-smelting furnace. Pilot-scale tests in an 800-kV-A electric-arc furnace demonstrated that 98.4 pct of the contained copper can be continuously recovered as metal by operating at bath temperatures between 1,350° and 1,375° C. Smelting rates of approximately 225 lb of blend ft2 of bath surface/hr resulted in power consumptions of approximately 520 kW-hr/ton of blend. The blister copper that was produced contained less than 0.1 pct iron while the precious metals reporting to the copper product and gangue material elimination were similar to those in a conventional smelting operation.

Jan 1, 1976

Major producers posted 25¢-per-pound increases on cadmium, raising their domestic quotes to $2.75 per pound. COBALT: Cobalt consumption in February, exclusive of salts and driers, increased by 21 percent compared with consumption in January. Significant increases in consumption occurred in cutting and wear resistant materials, welding and alloy hard-facing rods and materials, magnetic alloys, and other alloys. The major sales agency for cobalt in New York reportedly announced price increases, effective April 15, 1976, for cobalt metal, powders, and oxide. The new price for 250 kilo (551 lb.) drums of cobalt metal (granules or electrolytic cathodes), f.o.b. Port of New York, was quoted at $4.40 per pound. This is the first cobalt price increase since January 23, 1975, and is the result of a price increase by Sozacom, the official Zairian sales agent. Other cobalt producers are expected to raise their prices in line with the new quote.

Jan 1, 1976

By N. H. Snyder

THE Bureau of Mines has been active in promoting the purchase of coal for Government use under specifications that define the requirements in terms of heating value of the coal, expressed in British thermal units, and the com-position as shown by proximate analyses. To these, when required, are added the fusing temperature of ash, Hardgrove grindability index, and the free-swelling index. Under most of these specification contracts the bidders guarantee the quality of coal, and that guaranteed by the successful bidder becomes the standard of his contract. The deliveries are sampled in accordance with instructions 4 issued by the Bureau; the samples are analyzed in the Bureau's laboratory to determine whether the coal is of the quality guaranteed by the contractor and, if it is not, a price adjustment is made. Analyses of delivered coal and "tipple" samples (samples collected at mine tipples as coal is being loaded into railroad cars or trucks) are valuable data for use in evaluating future bids. Moreover, the continuous sampling of coal as delivered is a check on the practical results obtained in burning the coal.

Jan 1, 1953

By N. Fragen, H. H. Stroch

"INTRODUCTION A previous paper by H. H. Storch 4 described. three processes for the production of potassium sulphate from polyhalite (K2S01.MgSO1.2CaS04.2H2o), Since these processes depended upon calcination of polyhalite followed by leaching with water at 100°C., the fundamental reactions occurring in these steps were discussed in detail. This paper, which describes processes producing syngenite (K2S04.CaSO4.H2O) and potassium sulphate and gives data concerning the production of by-product magnesia, presents the results of work performed at the Non metallic Minerals Experiment Station of the U. S. Bureau of Mines, maintained at New Brunswick, N. J., in cooperation with Rutgers University.A study of the solubility relationships of the system 5 Ca++ -Mg++ -K+-SO4 = H20 at 25ºC. shows that syngenite is stable in the presence of a concentrated MgSO4 solution, the K2SO : equilibrium concentration being comparatively low (2.6 per cent), The processes described below, which involve the conversion of calcined polyhalite to syngenite, are based on the 25°C. equilibria. It has further been found that syngenite can be decomposed by water at 100ºC, yielding a 9 to 10 per cent K250 solution, the solid phase being potassium calcium pentasulphate (K2SO, 3CaSO.H2O, hereafter referred to as ""pentasulphate""). This latter compound is unstable in the presence of water at 25°C., its decomposition resulting in a solution containing about 3 per cent of K2SO4 and a solid phase consisting of gypsum. This behaviour of syngenite with water at 100°C. and of pentasulphate with water at 25ºC. constitutes the basis of processes for the production of K2SO4 by way of the conversion of calcined polyhalite to syngenite,Syngenite is a product which may be used as a fertilizer per se. As produced in the process to be described, it contains about 50 per cent of K2SO1, and will readily give up its potash content on treatment with water, although the limiting concentration at ordinary temperatures is approximately 3 per cent. This definite but limited solubility should make this product more desirable as a fertilizer then the more concentrated forms of potash salts which have higher solubilities and hence involve the danger or plant injury due to a high local concentration of potash."

Sep 1, 1931

The importance of controlling respirable dust and methane gas levels in underground coal mining cannot be underestimated. While respirable dust can significantly affect the occupational health of underground coal miners, methane gas accumulations pose significant safety concerns for these same workers. Water sprays and machine mounted dust scrubbers offer effective control of respirable dust exposures and methane gas accumulations. Water must not only be applied carefully to avoid dust rollback to the machine operator but must create sufficient turbulence to remove dead zones that could contain high concentrations of methane gas. While the flooded-bed dust scrubber has been generally responsible for decreased worker exposures to respirable dusts, this device has proved effective in controlling methane levels at the face. This paper reviews practical applications of water sprays and dust scrubbers to control respirable dust and methane gas on continuous miner faces.

By John H. Johnson

A study of mine air quality was conducted using the latest advanced continuous monitoring instruments. An overview of the various interacting variables in the mine that affect air quality is presented. One effort involves the evaluation of portable instruments, the development of measurement techniques, sample analysis procedures and computer programs for statistical analysis of measurement data, and the application of the instruments and techniques to the measurement of the concentrations of CO, CO2, NO, NO2 and particulate matter in a lead and a copper underground mine. A second effort involves the first application of the Mine Air Monitoring Laboratory (MAML), a mobile trailer containing laboratory type instruments, sampling and data systems for the measurement of CO, CO2, NO, NO2 and particulate matter. The data from the MAML for blasting and for operating diesel equipment are analyzed and presented in various plots.

Jan 1, 1977